Method for molding leather sealing members



Oct. 14, 1969 z, MICA, ETAL 3,472,926

METHOD FOR MOLDING LEATHER SEALING MEMBERS Original Filed Feb. 5, 1964 5Sheets-Sheet 1 THE 2 INVENTORS ANDREW Il. SEENANN LOUIS Z. MICAI MATTORNEYS @6&0 1959 L Z M|A| ETAL 3,472,926

METHOD FOR MOLDING LEATHER SEALING MEMBERS Original Filed Feb. 3, 1964 5Sheets-Sheet 2 INVENTORS ANDREW Il. SEEMANN LOUIS Z. ICAI M @f/Mg,

ATTORNEYS 5 Sheets-Sheet 5 ATTORNEYS ET L L. 2. MECA! @du M9 'M69 METHODFOR MOLDING LEATHER SEALING MEMBERS Original Filed Feb. 3, 1964 Oct. 14,1969 L, z, M|^| ETAL 3,472,926

METHOD FOR HOLDING LEATHER SEALING MEMBERS Original Filed Feb. 3, 1964 5Sheets-Sheet 4 ATTORNEYS Od. 14, 1969 L, z, M|A| ETA?. 3,472,925

METHOD FOR MOLDING LEATHER SEALING MEMBERS original Filed Feb. s, 1964 Ssheets-sheet 5 E lo? l lo. "7 |08 O5 le @v |09 HGMR BLAST us 36 ICONxoe\` law mvENToRs ANDREW l. SEEMANN LOUIS Z.IICAI BY d JJ ATTORNEYSUnited States Patent O 3,472,926 METHOD FR MGLDING LEATHER SEALINGMEMBERS Louis Z. Micai, Portola Valley, and Andrew M. Seemann,

Sunnyvale, Calif., assignors to Federal-Mogul Corporation, Detroit,Mich., a corporation of Michigan Original application Feb. 3, 1964, Ser.No. 342,097, now Patent No. 3,324,511, dated June 13, 1967. Divided andthis application Feb. 1S, 1967, Ser. No. 632,850 Int. Cl. B29b 7/24 U.S.Cl. 264-292 6 Claims ABSTRACT OF THE DISCLOSURE Leatherlubricant-sealing members are molded from pre-cut flat leather annulardiscs by stretching the inner periphery to increase its diameter whiledistorting an inner portion to a frusto-conical shape. The outer portionis formed to a cylindrical or flat annular shape, and the whole ismolded. No after-trimming is needed.

This application is a division of lapplication Serial No. 342,097 filedFeb. 3, 1964, now Patent No. 3,324,511.

This invention relates to an improved method for molding leather andmore particularly for molding annular leather lubricant-sealing members.

Leather sealing members for oil and grease seals have normally been madeby first molding or otherwise shaping a leather disk or ring to providea lip portion and a support portion, and then trimming olf the inner andouter peripheries, usually by a knife, to define the inner sealing lipedge and the outer edge of the anchoring portion. In some instances, theattempt was made to avoid trimming by pinching olf the peripheriesduring molding, and in a few instances attempts have been made to moldthe seals to size from pre-cut annular blanks, but heretofore theseprocedures have not proven satisfactory for large production runs,primarily because of the number of rejected pieces that have resulted. Adifficulty with molding the lips from pre-cut blanks was that the moldstended to pinch olf portions of the leather, and in an irregular,unpredictable manner, so that while some parts were accurately made,many other parts were quite unsatisfactory and had to be discarded.

An object of this invention is to provide a method which rapidly andaccurately manufactures leather sealing elements from pre-cut leatherwashers, doing so without any trimming being required during the moldingprocess or afterwards and doing so without pinching olf peripheralportions.

An advantage of the invention is that it saves leather. Conventionaloperations, which relied on trimming for providing the final lip shape,resulted in pulling in the leather outer periphery unevenly orelliptically; hence, extra leather had to be used in order for acylindrical trim to be obtained. The trimmed-olf margin around the outerperiphery has typically been 1A to 1/2" wide, and this entire margin waswaste. The present invention eliminates these margins and the blanks canbe spaced next to each other. Hence, the leather blanks for the sealscan be made smaller, and more seals can be made per hide.

Trim operations tended to become inaccurate for a variety of reasons,such as careless setup by the operator, improper trim button iit, andthe condition of the trim knife-even a sharp knife normally left a burr,and dull knives left worse burrs; moreover, dull knives were commonbecause it was common for the knives not to be changed often enough. Inthe present invention the trim operation is eliminated, and the blankslare punched out swiftly and accurately with precise inner and outerperipheries.

3,472,926 Patented Oct. 14, 1969 ICE Conventional leather molds werehand-aligned, the operator obtaining alignment by tapping them with alead hammer. The mold of this invention is self-aligning. The dimensionsof the product made by this invention are also more stable than those ofprior art seals, since the distortions due to stresses inherent inhat-type molds are not present.

Other objects and advantages of the invention will appear in thefollowing description of a preferred form of the invention.

In the drawings:

FIG. 1 is a view in elevation and in section of an apparatus embodyingthe principles of the invention and comprising a mold for leatherwashers, shown in its open position.

FIG. 2 is a view similar to FIG. l showing the mold as it begins toclose, with a spring-urged stud carried by the upper half of the molddepressing a weaker springurged lower mold half.

FIG. 3 is a similar view showing the mold in the next state, in whichthe lower mold half has been fully depressed, and the stud itself isbeing urged upwardly against its spring.

FIG. 4 is a similar view of the mold in its fully closed or curingposition.

FIG. 5 is a similar view, showing the mold as it begins to open and hasreached the position where the lower spring has once again pushed up thespring-loaded lower mold half and the upper spring has begun to separatethe relatively movable parts of the upper half of the mold.

FIG. 6 is "a similar view, showing the mold in its fully opened positionwith the molding completed.

FIG. 7 is an enlarged fragmentary view of the bottom right-hand portionof the upper mold half.

FIG. 8 is a view similar to FIG. 4 of a modified form of the inventionfor making a so-called barrel type of annular sealing element, with themold shown in its closed position.

FIG. 9 is an enlarged fragmentary view of the bottom right-hand portionof the upper mold half of FIG. 8.

FIG. l0 is a view like FIG. 8 with the mold open most of the way.

In general, the invention uses a novel method of molding an annularsealing element 50 or 101 having a frustoconical lip 60 or 102 from a atleather Washer. In this method an outer marginal portion of the washeris loosely supported and the inner periphery is forced down whilestretching it radially outwardly and widening the inner periphery, sothat an inner marginal portion assumes a truste-conical shape. At thesame time, the outer periphery is pulled in. The inner periphery isforced out to a predetermined inner diameter while continuing to shapeit, and the Washer is clamped and molded in the desired shape at thepredetermined diameter. The forcing and shaping is done by insertingthrough the inner periphery of the washer a tapered portion of a moldmember with an initial portion smaller than the opening through thewasher and widening out to a greater width, so as to force the innerportion of the washer in the same direction while its outer margin isbeing held on a loose support, putting it into the frusto-oonical shape.Continued forcing of the tapered portion stretches the inner peripheryto a predetermined size while simultaneously pulling in the outerperiphery. The tapered portion is succeeded by a cylindrical mandrelportion having the predetermined diameter to which the inner peripheryof the washer is to be stretched. This cylindrical portion, in turn, issucceeded by a frusto-conical portion which holds the inner portion ofthe washer in the desired shape while molding it there under pressure.The outer portion may be flat (FIGS. 1-7) or cylindrical (FIGS. 8-10)depending on the type of oil seal being made. The process will be betterunderstood by noting the structure of the molds and their operation, andthese will therefore be described now.

The mold shown in FIGS. l through 7 comprises an upper mold assembly 11and a lower mold assembly 12. These assemblies are suitably mounted inthe usual press which applies the desired pressure and closes the mold10.

The upper mold assembly 11 comprises a mold platen 13, an uppermold-half 14, and a spring-loaded stud 15. A stem portion 16 of the stud15 protrudes through a recess or opening 17 in the bottom of the uppermoldhalf 14, and its head 18 rests on a shoulder 19 of the mold-half 14.A spring 20, confined between the stud head 18 and an upper end wall 21of an upper recess portion 22 in the upper mold platen 13, urges thestud downwardly and normally seats the head 18 against the shoulder 19.The upper mold-half 14, which is rigidly secured to the mold platen 13by bolts 29, has a congurated seal-molding portion 23 that will bediscussed in detail later; this portion 23 extends generallyfrusto-conically between a lower annular end 24 of the mold-half 14 andan upper annular shelf 25 that is joined by a cylindrical portion 26 toa flat outer rim 27. The upper mold-half 14 also has an air-release orventing passage 28.

The lower mold assembly 12 includes a mold platen 31, a mold base 32mounted thereon, a ring 33 holding the base 32 in place, and aspring-loaded lower mold-half 35, whose spring 36 is of lighter pressurethan the spring 20 in the upper mold assembly 11. The base member 32preferably has an annular outer rim portion 37 with a frusto-conicalbearing ball 38 against which a frustoconical bearing portion 39 of thehold-down ring 33 engages, and bolts 40 secure the hold-down ring 33(and therefore the base member 32) to the platen 31. The mold base 32has a fiat upper end 41 which is recessed to provide an annular shelf 42that locates and helps to support the leather washer 50 which is to bemolded. The mold base 32 also is provided with a central wall 43 having,successively, an upper tapered inner periphery 43a, an upper cylindricalportion 48, a frusto-conical step 44, and a lower wider cylindricalportion 49.

The lower mold-half 35 is provided with a frustoconical step 45 matchingthe step 44 of the base, and connecting inner and outer cylindricalperipheries 46 and 47. The peripheries 46 and 47 match the cylindricalinner peripheral portions 48 and 49 of the well 43, which are joined bythe step 44, and these surfaces guide the vertical movement of the lowermold-half 35 in the well 43 when it is urged down by the stud 15 againstthe pressure of the spring 36 during closure of the mold 10. Preferably,the spring-mounted lower mold-half 35 is spaced radially inwardly swayfrom the upper tapered portion 43a of the well 43 by a gap 51.

The upper end of the spring-loaded lower mold-half 35 is provided with aleather shaping and molding section 52 that bounds the lower part of themold cavity. This section 52 comprises an inclined lower shelf 53 and aninclined side wall 54. The upper end 55 of the section 52 is tlat, andwhen the steps 44 and 45 bear against each other the at end 55 is levelwith the recessed shelf 42 of the base 32. This is the extreme upperposition of the lower mold-half, to which it is urged by the spring 36.Below the shelf 53, a cylindrical portion 57 leads to a iiat bottom wallor webb 56. When the lower mold-half 35 is fully bottomed on the plate31 it is in its extreme lower position, and then the end 55 is levelwith a shelf 58 at the lower end of the tapered portion 43a. Ventpassages 70 and 71 are provided respectively in the lower moldhalf 35and the mold base 32.

The understanding of the principles involved can now best be explainedby following through the cycle of operations shown in FIGS. 1 through 6.

In FIG. l, a leather washer 50, which was punched out to an exact sizewith precise inner and outer peripheries, has been placed on the upperend 55 of the lower moldhalf 35 and on the annular support shelf 42,which in this position of the mold 10 is level with the end 55. Theupper mold assembly 11 is about to be lowered, and its stud 15 is fullyprojected by the spring 20.

As the mold 10 closes, the stud 15 comes against the central surface orweb 56 of the lower moldhalf 35 and begins to move the lower mold-half35 down into the well 43, as shown in FIG. 2, since the lower spring 36is of lighter weight than the upper spring 20, and therefore yields toit. As the lower mold half 35 moves down, compressing the spring 36, theshelf 42 provides for awhile all the support for the leather washer 50,and the entire inner portion of the leather washer 50 is free. Uponfurther downward movement of the upper mold assembly 11, the uppermold-half 14 comes into contact with the inner periphery 59 of theleather washer 50 and to begin to force it down evenly into afrusto-conical shape which, at this stage, is of different taper thaneither mold-half 14 or 35. This is shown in FIG. 2, which also showsthat the loosely supported outer portion of the washer 50 is beingpulled in due to this action.

The stud 15 continues to push the lower mold half 35 down toward theplaten 31 until the lower mold half 35 is fully bottomed in the well 43on the platen 31, as in FIG. 3. This places the lower mold-half 35 inits molding position with its upper end 55 level with the shelf 58 ofthe lower mold base 32. With the lower mold-half 35 bottomed, the stud15 begins to compress its spring 20 as the upper mold-half 14 continuesto descend. Now, instead of simply moving parallel to and as the samerate as the lower mold-half 35, the upper mold-half 14 continually movescloser to the lower mold-half 35 and therefore begins to close the moldcavity, drawing the leather washer 50 on the mold half 14 as it does so.

Mold closing continues until the fully bottomed, fully closed positionshown in FIG. 4 is reached, where the bottom 24 of the upper mold-half14 rests on the web 56 of the lower mold-half 35, to distribute moldingpressure, and the rim 27 of the upper moldhalf 14 is seated on the upperend 41 of the lower mold base 32. The leather washer 50 is confinedbetween the upper mold-half 14 and the lower mold-half 35, and theclosed mold cavity defines a frusto-conical sealing lip 60 of the seal,while a flat flange 61 is enclosed between the upper end 55 of the lowermold half 35, the shelf 58 of the lower mold base 32, and the shelf 25of the upper mold-half 14. This is the final shape of the leathersealing member 62. As noted earlier, the leather washer 50 was punchedto an exact size beforehand so that it fits perfectly into this newshape, having been drawn to it by the mold 10.

During the shaping of the washer 50 to the sealing element 62, from FIG.2 to FIG. 4, the configuration 23 of the upper mold-half 14 is veryimportant. It is shown more clearly in the enlargement, FIG. 7. Theshape 23 assures proper passage of the leather washer 50 into the moldcavity as the mold closes and helps to prevent pinching off andmisalignment. A tapered surface 63 first engages the inner surface 59 ofthe washer 50 and assures centering of the washer 50 in the mold cavityas the taper 63 moves down. The taper 63 ends at a short cylindricalportion 64. As the inner periphery 59 of the washer 50 slides againstthe tapered surface 63, it is forced downward and dilated until itassumes its molded diameter, which is the same as that of thecylindrical portion 64. Then the washer 50, as it is shaped further,slides over the short cylindrical portion 64 and comes to rest againstthe actual mold surface 65, which is tapered or frustoconical to matchthe desired slope of the lip 60.

Normally, the leather washer will have been coated, preferably on bothsurfaces but not on the edges, as provided in U.S. Patent 2,845,267, toprovide a lowfriction elastomeric coating, and this elastomeric coatinghelps the molding process by providing surfaces that have minimumfriction characteristics so that the washer can slide over theconfiguration 23. Of course, it is possible to mold the leather withoutany such treatment so that it will be pre-shaped, but it is normallypreferred to have the elastomeric coating on, and when that is present,the tmold is heated in the normal way and it remains closed until theleather is assured of retaining its molded shape.

When the molding operation has been completed the mold 10 opens, theparts moving in the reverse order from which they moved during theclosing of the mold. FIG. 5 shows the position occupied when the stud 15has again become fully retracted and when the upper moldhalf 14 hasmoved up enough so that the spring 36 can push the lower mold-half 35part of the way up. The finished molded member 62 is being movedupwardly, carried by the lower mold-half 35.

When the position of FIG. 6 is reached the mold 10 is again in its openposition, and the finished article 62 can be ejected, as by an air blast66. Some of the air from this blast goes into the gap 51 between thelower mold-half 35 and the lower mold base 32 and gets under the flange55, lifting the seal 62 from the lower mold-half 35. Then a new elementcan be placed into the mold 10.

A modified mold 100 of the invention is shown in FIG. 8. This mold isused to solve a particularly difficult problem, that of manufacture ofso-called barrel-shaped leather sealing members 101 having afrusto-conical lip 102 succeeded by an axially extending cylindricalanchor portion 103. The manufacture of seal elements of this type isgenerally considered to be much more difficut than that of elements likethe seal 60. The difficulty is that the leather has had to be forceddown into the mold by pushing on the upper edge 104, for there is nolarge flange by which to push it. However, the present invention makesit possible to make such seals 101` just as easily as those of the typeshown in FIGS. 1-6.

Basically, the mold 100 is like the mold 10, with the exception of theshape of the mold cavity and the length of some of the portions. Themold 100 includes an upper mold assembly 10S and a lower mold assembly106. The upper mold assembly 105 comprises a mold platen 107, an uppermold ring 108, and a spring-loaded upper moldhalf 109 which is projectedout through the mold ring 108 by a spring 110. The upper mold half 109has a congurated portion 111, which is succeeded by a tapered moldingportion 112, and this is followed by a cyindrical portion 113, the lowerportion of which defines part of the mold cavity while the upper portionextends up through the mold ring 108. A radial horizontal moldingportion 114 of the mold ring 108 engages the upper edge 104 of theleather. A cylindrical portion 115 is succeeded by an annular fiatradial portion 116. The upper mold-half 109 has a collar 117 forengagement of the shoulder 118 on the ring 108 and for engagement of thespring 110.

The lower mold assembly 106 includes a mold platen 120, a mold base 121,and a hold-down ring 122 with bolts 123 which operate as in the mold 10.The mold base 121 has an upper end 124 upon which portion 116 of theupper mold half 108 seats when the mold 100 is in the fully closedposition shown in FIG. 8. The base 121 has a shelf 125 upon which theleather washer is seated when the mold 100 is open, before operation,and from which it is pulled away during the molding operation. The interior wall of the base 121, instead of being tapered, has a cylindricalwall 126 joined 'by a curved edge 127 to the shelf 125, `and the wall126 is succeeded by a tapered portion 128 that leads into a cylindricalportion 129.

The lower mold assembly 106 also includes a lower mold-half 130 which isbasically like the member 35 discussed earlier and has, for moldingpurposes, a shelf 131 that receives the lower edge 119 of the leatherelement 101 during the molding; the shelf 131 meets an inclined portion132 which ends in a rather sharp point in the upper end 133. There is agood close fit between the outer periphery 134 of the lower mold-half130 and the cylindrical periphery 129 of the well in the mold basemember 121. The lower mold-half 130 is mounted on a spring 135 which islighter than the spring 110.

The configuration 111 of the upper mold-half 109 is an important featureof this invention and is shown more clearly in the enlargement, FIG. 9.The shape 111 assures passage of the leather washer into the mold cavityas the mold closes. A tapered surface 140 first engages the innersurface of the washer 101 and assures centering of the washer in themold cavity as the taper 140 moves down. The taper 140 leads by a shortcylindrical portion 141 to a narrow ledge 142, and as the innerperiphery of the washer 101 slides against the ledge 142, the uppermold-half 109 is enabled by the ledge 142 to hold the washer 101 morefirmly during the initial closing movement. Then the washer 101 slidesby the ledge 142 onto the tapered portion 143 and moves up a shortcylindrical portion 144 to come against the actual mold surface 112,which is tapered to match the desired slope of the lip. (Note that theportions 143, 144 and 112 correspond to the portions 63, 64 and 65 ofthe mold 10.)

Sequential operation of the mold is substantially the same as that ofthe mold 10, and the order of operation is substantially the same.However, in addition to forming the frusto-conical portion 102, theprepunched leather washer is pulled down along the inner peripheralsurfaces 126, 128, and 129 of the mold base member 121 into an axialextending cylindrical portion 103, and then its upper edge 104 isengaged by the upper mold-half 108 when the portion 116 seats againstthe surfaces 124 of the lower mold base 121. When the mold 100 is opened(FIG. l0), an air blast 136 is introduced at the angle shown to stripthe finished seal 101 from the mold member 109.

To those skilled in the art to which this invention relates, manychanges in construction and widely differing embodiments andapplications of the invention will suggest themselves without departingfrom the spirit and scope of the invention. The disclosures and thedescription herein are purely illustrative and are not intended to be inany sense limiting.

What is claimed is:

1. A method of molding a leather sealing element having a frusto-conicallip from a flat leather annulus, comprising the steps of:

stretching the inner periphery of the annulus to increase the diameterof the opening of said annulus while distorting the annulus into afrustum of a cone,

then distorting a zone near the base of the frustum into a cylindricalsection, and

then compression molding the leather element so formed into a finaldesired shape.

2. A method of molding a leather sealing element having a frusto-conicallip from a flat leather annulus, comprising the steps of:

stretching the inner periphery of the annulus to increase the diameterof the opening of said annulus while distorting the annulus into afrustum of a cone,

then distorting a zone near the base of the frustum into a fiat annularsection, and

then compression molding the leather element so formed into a finaldesired shape.

3. A method of molding an annular sealing element having afrusto-conical lip from a fiat leather washer with an inner peripheryadjacent which is an inner marginal portion, and an outer peripheryadjacent which is an outer marginal portion, comprising the steps of (l)supporting said outer marginal portion of said washer,

(2) forcing the inner periphery of the washer down while stretching thewasher radially outwardly and widening the inner periphery, so that saidinner marginal portion assumes a frusto-conical shape, while pulling theouter periphery in,

(3) forcing the inner periphery out to a predetermined inner diameterwhile shaping the outer marginal portion of said washer, and

(4) clamping and compression molding said washer so formed into a finaldesired shape at said predetermined inner diameter.

4. A method of molding an annular sealing element having afrusto-conical lip and an annular outer flat portion from a at leatherwasher having an inner periphery with an inner marginal portionthereadjacent and an outer periphery with an outer marginal portionadjacent said outer periphery, comprising the steps of:

(l) supporting said outer marginal portion of said washer,

(2) forcing the inner periphery down while stretching said washerradially outwardly and while widening the inner periphery, so that saidinner marginal portion assumes a frusto-conical shape and while pullingthe outer periphery radially in,

(3) forcing the inner periphery to a predetermined inner diameter whilecontinuing to shape said inner marginal portion.

(4) distorting said outer marginal portion into a planar section, and

() clamping and compression molding said washer with an innerfrustoconical portion having said predetermined inner diameter and anouter planar portion.

5. A method of molding an annular Sealing element having afrusto-conical lip and a cylindrical outer annular portion from a flatleather washer having an inner periphery, an inner marginal portion, anouter periphery, and an outer marginal portion, comprising the steps of:

(l) loosely supporting said outer marginal portion of said washer,

(2) forcing the inner periphery down while stretching it radiallyoutwardly and widening the inner pe riphery, so that said inner marginportion assumes a frusto-conical shape, and while thereby pulling theouter periphery in,

(3) forcing the inner periphery out to a predetermined inner diameterwhile continuing to shape said inner marginal portion,

(4) drawing the outer marginal portion in and distorting said portioninto a cylindrical shape, and

(5) fully enclosing said washer in a mold and compression molding it ina shape having a cylindrical outer portion and a frusto-conical innerportion.

6. A method of molding a sealing member with a frusto-conical lip from ailat annular leather washer having an inner periphery, an inner marginalportion, an outer periphery, and a outer marginal portion, comprisingthe steps of:

(l) loosely supporting the outer peripheral margin only of said washer,

(2) inserting through said inner periphery a tapered member that has aninitial portion smaller than the opening through said washer and widensout to a greater width, so as to force the inner marginal portion ofsaid washer in the same direction on said loose support, putting it intoa frusto-conical shape,

(3) continuing to force said tapered member to stretch said innerperiphery to a predetermined size while simultaneously pulling in theouter periphery,

(4) pushing a cylindrical mandrel having a predetermined diameterthrough said opening in the same direction,

(5) distorting said outer peripheral margin into a desired shape, and

(6) clamping said washer with said inner margin held in a frusto-conicalshape at said predetermined diameter and with said outer margin in adesired shape and compression molding said washer into a final desiredshape.

References Cited UNITED STATES PATENTS 1,183,956 5/1916 Collins et al.1,872,269 8/1932 Frederick 264--320 X 3,045,287 7/1962 Yost et al.264-292 X 3,115,678 12/1963 Keen et al. 264-322 X 3,173,342 3/1965Wilson 264-320 X ROBERT F. WHITE, Primary Examiner I. H. SILBAUGH,Assistant Examiner U.S. Cl. XR. 264-296, 320

